1. Field of the Invention
The present invention relates to a wireless terminal device and a communication method that selectively switch among a plurality of communication systems for performing communication.
2. Related Art
In recent years, LTE (Long Term Evolution) type communication systems have been introduced as communication systems used by wireless terminal devices such as a mobile telephone device, in addition to Circuit Switched (CS) type communication systems (for example, CDMA).
In addition, a CS-Fallback function has been defined in 3GPP TS 23.272. With this function, it is possible to notify in an LTE communication system an incoming call request from a CDMA communication system (For example, refer to 3GPP TS 23.272 V10.3.1, “Circuit Switched (CS) fallback in Evolved Packet System (EPS); Stage 2” 2011-04).